High pressure discharge lamps, such as xenon metal halide lamps, employ an electronic ballast circuit for starting the lamp, and for powering the lamp during steady state lamp operation. High pressure discharge lamps, especially those operating at pressures greater than about 0.5 atmospheres, require a very high voltage impressed across the lamp to start. Such starting voltage typically exceeds more than about 15,000 volts, and may even exceed more than about 20,000 volts. A prior art approach to designing an appropriate electronic ballast circuit has been to utilize two separate sets of electrical components: one set of components for starting the lamp and another set of components for running the lamp.
As a general matter, however, it is desirable to reduce the number of electrical components that make up an electronic ballast circuit. This reduces the cost of the circuit, and also its size, a factor becoming increasingly important in size-limited environments, such as in automobiles. It would, accordingly, be desirable to provide an electronic ballast circuit for a high pressure discharge lamp that requires fewer parts to implement a lamp-starting function.